RDLN High-Speed Gear Set (17/49) – GY6 50cc / 139QMB

Description

Is your 50cc 139QMB engine revving at its limit without a higher top speed? The RDLN 17/49 Performance Gear Set changes your final drive ratio from the stock 3.41–3.71 down to 2.88, allowing your engine to push the bike faster at lower RPMs. Depending on your engine mods and rider weight, this gear set can net up to 7+ MPH of top-end gain. It’s also the essential final step for scooters running 72cc, 80cc, or 100cc big bore kits — eliminating the over-revving that comes with stock gearing on a bored engine.

Key Features

• 2.88 Final Drive Ratio: Down from stock 3.41–3.71 — up to 7+ MPH top-end gain.
• Ideal Big Bore Pairing: Eliminates over-revving on 72cc, 80cc, and 100cc kits.
• Forged and Hardened Steel: Precision-cut to withstand increased torque of performance engines.
• Balanced Configuration: 17/49 delivers the best acceleration-to-top-speed balance for the QMB139 platform.
• Reduces Cruising RPMs: Improves fuel economy and long-term engine wear at speed.

Specifications

• SKU: 1200-1283
• Teeth Count: 17T pinion / 49T large gear
• Final Drive Ratio: 2.88
• Weight: 540g
• Material: Forged hardened steel
• Installation: Requires hydraulic press

Compatibility

Fits 139QMB / 1P39QMB engine cases found in nearly all 50cc 4-stroke Chinese scooters, including engines coded:

Installation Note: This is not a drop-in part. A hydraulic press is required to remove old gears from the secondary shaft and press the RDLN gears on. Professional installation is strongly recommended.